A K-band slot antenna element with integrated GaN (gallium nitride) power amplifier (PA) is presented. It has been optimized through a circuit-EM co-design methodology to directly match the transistor drain output to its optimal load impedance (Zopt = 17 + j46Ω) while accounting for the over-the-air coupling effects in the vicinity of the transition between the PA and antenna. This obviates the need for using a potentially lossy and bandwidth-limiting output impedance matching network. The measured PA-integrated antenna gain of 15 dBi with a 40% total efficiency at 28 dBm output power agrees well with the theoretically achievable performance targets. The proposed element is compact (0.6 × 0.5 × 0.3 λ 3), and thus well-suited to meet the high-performance demands of future emerging beamforming active antenna array applications. Index Terms-millimeter-wave antennas, gallium nitride (GaN), active integrated antennas, power amplifiers, antenna-circuit co-design, K-band, antenna array element.

A bandwidth-enhanced 8 × 8 cavity-backed slot array antenna for fixed beam applications is presented. The antenna consists of four 2 × 2 subarrays fed by ridge gap waveguide and a modified bow-tie coupling slot in the cavity layer. The proposed bow-tie coupling slot provides additional 10 % impedance bandwidth as compared to the traditional rectangular coupling slot. The fabricated prototype demonstrates an |S11| ≤ −10 dB fractional impedance bandwidth and a 3 dB gain-drop bandwidth of approximately 28 % and 25 %, respectively, with peak gain of 26.4 dBi, aperture efficiency > 60 % and cross-polar discrimination > 40 dB. Measurements show good agreement with simulations. Moreover, we show the impact of the dimensions and shape of the cavity coupling slot on the bandwidth enhancement. The bandwidth enhancement is explained by the double-ridge slot behavior of the bow-tie coupling slot, which shows a more wideband behavior than the traditional rectangular coupling slot behaving like a cross-section of a waveguide.

The potentialities of the GaN monolithic technology for the growing microwave backhaul power amplifier market are discussed in this paper. To support this discussion, two GaN monolithic Doherty power amplifiers for 7 GHz backhaul applications are presented. They exhibit 5W output power, with almost 10 dB gain, and high efficiency at 7 dB output power backoff.\ud In particular, one module has been optimized for maximum efficiency at center frequency (47% at 7 dB output power backoff), while the other for high efficiency on a larger bandwidth (15% fractional bandwidth)

A high equivalent isotropic radiated power (EIRP) active phased array antenna is proposed for 5G communication systems at 28 GHz. The numerical design, the measurements of a fabricated prototype and the performance analysis are presented. The antenna design is based on the gapwaveguide technology and consists of 16 × 16 single 45 • slant-polarized elements. The proposed design employs a low complexity printed circuit board (PCB) structure with only six layers, i.e., a half of existing wideband solutions. The array antenna incorporates up/downconverter integrated circuits (UDCs) and 1 × 4 transceiver beamformer integrated circuits (BFICs). Moreover, a compact and highly efficient transition at the end of each channel of the BFICs has been designed to interconnect the antenna elements with the PCB. The antenna's frontend loss, which includes the feed line, mismatch, and ohmic losses, is only 1.3 dB. The array covers the scanning range of ±60 • in the azimuth plane and ±10 • in the elevation plane. The S 11 < −10 dB frequency bandwidth is from 26.5 − 29.5 GHz. The maximum EIRP of the antenna is 65.5 dBm at saturation point. The presented design offers a compact, robust and low loss performance solution meeting the high transmission power requirements of 5G applications.

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